In a broadband wireless access system under a typical cellular environment, as time goes by during communications, the communication condition with other neighbor base stations may be better than a previous serving base station because of movement or propagation environment change of a subscriber terminal, or sudden increase of subscriber terminals in a particular cell. In this situation, the subscriber terminal, the serving base station, and the neighbor base stations have to efficiently recognize the change in the communication environment and to establish a communication path anew using an optimal base station.
In a conventional method, when a handover to a neighbor cell or a neighbor sector is needed according to changes in the communication environment of the user, the user terminal synchronizes with neighbor base stations based on a MOBile_NeighBoR-ADVertisement (MOB_NBR-ADV) message and a MOBile_SCaNning-ReSPonse (MOB_SCN-RSP) message from the serving base station and conducts a scanning process to measure the channel status. The scanning process is performed with neighbor base stations in sequence based on a neighbor base station list contained in the MOB_NBR-ADV message.
Since the conventional MOB_NBR-ADV message is broadcasted to every user within the cell at the same time, the message should include information relating to every neighbor base station to which the users may hand over. Accordingly, when a plurality of indoor base stations is present in the cell or when multiple communication modes are present in the same space and base stations of the various modes are mixed up, the number of the base stations recorded in the MOB_NBR-ADV message increases. At the base station, disadvantageously, the capacity of the message carrying the information relating to the neighbor base stations rises. At the terminal, as the number of the base stations to scan increases, the scanning duration is lengthened. Ultimately, the data reception time from the existing base station is decreased by the scanning duration, thus lowering the system throughput and raising the power consumption during the scanning.